A porosity method to describe the influence of internal structures on a fluid flow in case of fast dynamics problems

Abstract

To account for the influence of a complex set of solid structures among a fluid flow, without meshing the structures, a concept of ‘equivalent porosity method’ was developed. Structures are considered as solid pores inside fluid and are globally described by three parameters: a porosity, a shape coefficient and a pressure loss coefficient. The method was adjusted for fast dynamics problems, described with a Eulerian formulation and involving monophasic fluids going through a structure net of irregular shape. A numerical model was implemented in the hypothetical core disruptive accident (HCDA) constitutive law of the EUROPLEXUS computer code. The model was validated on an analytical shock tube test, schematising a horizontal slice of a liquid metal fast breeder reactor in case of HCDA (explosive phenomenon). A short parametric study tests the influence of the description of structures on the propagation of a pressure wave through the shock tube. These results were used to simulate numerically a HCDA in a scale model of a reactor.